[LLVMdev] [cfe-dev] How to increment a Global Variable in a LLVM module?

[Reid Kleckner]

Also, this a question for llvm-dev, not cfe-dev.

On Thu, May 14, 2015 at 10:33 AM, Reid Kleckner <rnk at google.com> wrote:

> Load it, add it, store it, and then for good measure, plug it, play it,
> burn it, and rip it. :)
>
> You just need to add a store to your IR:
> %cell_index = load i32* %cell_index_ptr
> %new_cell_index = add i32 1, %cell_index
> store i32 %new_cell_index, i32* %cell_index_ptr
>
> On Wed, May 13, 2015 at 9:23 PM, Kolmogorov <e-link at msn.com> wrote:
>
>> I want to add an instruction at the end of a basic block to increment a
>> GlobalVariable (using the LLVM C++ library). I am pretty new to to the
>> LLVM,
>> can I do this directly or does this require loading the global variable,
>> incrementing it by the desired value and writing back to the global
>> variable
>> ?
>>
>> Even if I load the variable (with LoadInst constructor), How will the
>> "Add"
>> instruction know where is the variable ?
>>
>> For example, look at this IR ocde : %cell_index = load i32*
>> %cell_index_ptr
>> %new_cell_index = add i32 1, %cell_index
>>
>> the add instruction knows on which variable to operate (cell_index). But
>> since I will create the load instruction from the C++ I don't know where
>> the
>> variable will be created. (I do not operate the IR code directly but using
>> the C++ it was just for the example
>>
>>
>>
>> --
>> View this message in context:
>> http://clang-developers.42468.n3.nabble.com/How-to-increment-a-Global-Variable-in-a-LLVM-module-tp4045533.html
>> Sent from the Clang Developers mailing list archive at Nabble.com.
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>>
>
>
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